Image projection apparatus

ABSTRACT

An image projection apparatus for projecting an image using light includes a light source configured to emit the light; and an operating unit configured to allow a user to operate the image projection apparatus, the operating unit being disposed above the light source when viewed from a placement surface on which a main body of the image projection apparatus is placed. The image projection apparatus also includes a first flow path in which air flows through the light source; and a second flow path different from the first flow path, the second flow path being formed between the light source and the operating unit.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of U.S.application Ser. No. 14/454,431, filed Aug. 7, 2014, which is acontinuation of U.S. application Ser. No. 13/644,687, filed Oct. 4,2012, which claims priority to Japanese Patent Application No.2011-242923 filed in Japan on Nov. 4, 2011. The entire contents of eachof the above are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image projection apparatus.

2. Description of the Related Art

Image projection apparatuses have been known that include digital mirrordevices (DMDs) serving as image forming elements that modulate light onthe basis of image data supplied from personal computers, for example,and image forming units having irradiation units irradiating the imageforming elements by light from light sources, and in which the imageforming units form images and the images formed by the image formingunits are focused on projection planes using projection opticalsections.

The image projection apparatuses use halogen lamps, metal halide lamps,or high-pressure mercury lamps as the light sources. These lamps reach ahigh temperature when emitting light. Japanese Patent ApplicationLaid-open No. 2002-244210 and Japanese Patent Application Laid-open No.2008-102374 disclose image projection apparatuses. In an example of theimage projection apparatuses, ambient air is taken in from an intakeport provided to the apparatus by an air supplying unit such as a bloweror a fan, the air taken in is supplied to a light source to cool thelight source, and air of which the temperature has increased by takingheat from the light source is discharged outside the apparatus via anexhaust port.

An operating unit serving as an input mechanism such as buttons for auser to operate the image projection apparatus is preferably disposed onthe upper surface of the image projection apparatus for allowing theuser to readily operate the image projection apparatus.

The temperature of the light source reaches up to about 1000° C. eventhough the light source is cooled by supplied air. As a result, airheated by the light source flows upward by air supplied from an airsupplying unit and its ascending air current. In addition, heat from thelight source is conducted toward the operating unit by thermalconduction. When the operating unit is disposed above or just above thelight source, a problem arises in that air heated by the light sourceand flowing upward, heat by the thermal conduction, and heat by naturalconvention collide with the operating unit disposed above or just abovethe light source and the operating unit is heated by the heated air andthe heat, thereby increasing the temperature of the operating unit.

Therefore, there is a need for an image projection apparatus capable ofsuppressing an increase in the temperature of an operating unit evenwhen the operating unit is disposed above or just above a light source.

SUMMARY OF THE INVENTION

It is an object of the present invention to at least partially solve theproblems in the conventional technology.

According to an embodiment, there is provided an image projectionapparatus for projecting an image using light. The image projectionapparatus includes a light source configured to emit the light; and anoperating unit configured to allow a user to operate the imageprojection apparatus, the operating unit being disposed above the lightsource when viewed from a placement surface on which a main body of theimage projection apparatus is placed. The image projection apparatusalso includes a first flow path in which air flows through the lightsource; and a second flow path different from the first flow path, thesecond flow path being formed between the light source and the operatingunit.

The above and other objects, features, advantages and technical andindustrial significance of this invention will be better understood byreading the following detailed description of presently preferredembodiments of the invention, when considered in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a projector according to anembodiment of the invention and a projection plane;

FIG. 2 is a ray diagram from the projector to the projection plane;

FIG. 3 is a schematic perspective view illustrating an internalstructure of the projector;

FIG. 4 is a schematic perspective view of a light source unit;

FIG. 5 is a perspective view illustrating optical system parts housed ina lighting unit and the other units;

FIG. 6 is a perspective view when the lighting unit, a projection lensunit, and an image forming unit are viewed from direction A of FIG. 5;

FIG. 7 is a schematic diagram explaining an optical path of light in thelighting unit;

FIG. 8 is a perspective view of the image forming unit;

FIG. 9 is a perspective view illustrating a first optical system unittogether with the lighting unit and the image forming unit;

FIG. 10 is a sectional view along line B-B of FIG. 9;

FIG. 11 is a perspective view illustrating a second optical system heldby a second optical system unit together with the projection lens unit,the lighting unit, and the image forming unit;

FIG. 12 is a perspective view illustrating the second optical systemunit together with the first optical system unit, the lighting unit, andthe image forming unit;

FIG. 13 is a perspective view illustrating an optical path from thefirst optical system to the projection plane;

FIG. 14 is a schematic diagram illustrating an arrangement of the unitsin the projector;

FIG. 15 is a schematic diagram illustrating an example of use of theprojector in the embodiment;

FIG. 16 is a schematic diagram illustrating an example of use of aconventional projector;

FIG. 17 is a schematic diagram illustrating an example of use of aprojector in which a light source and the lighting unit are arranged ina direction orthogonal to the projection plane;

FIG. 18 is a perspective view illustrating a placement surface side ofthe projector;

FIG. 19 is a perspective view illustrating the placement surface side ofthe projector when an open-close cover is removed from the projector;

FIG. 20 is a schematic diagram to explain an air flow in the projector;

FIG. 21 is a schematic diagram more specifically illustrating thestructure illustrated in FIG. 20;

FIG. 22 is a sectional view along line C-C of FIG. 21;

FIG. 23 is a sectional view along line D-D of FIG. 21;

FIG. 24 is a sectional view along line E-E of FIG. 21;

FIG. 25 is a sectional view along line F-F of FIG. 21;

FIG. 26 is a sectional view along line G-G of FIG. 21; and

FIG. 27 is a schematic diagram to explain a modification of theembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of a projector that is an image projection apparatus towhich the invention is applied is described below. FIG. 1 is aperspective view illustrating a projector 1 according to an embodimentand a projection plane 101 such as a screen. The projector 1 is alsoreferred to as the apparatus in the following description. In thefollowing description, the normal line direction of the projection plane101 is defined as an X direction, a short-axis direction (up-downdirection) of the projection plane 101 is defined as a Y direction, anda long-axis direction (horizontal direction) of the projection plane 101is defined as a Z direction.

As illustrated in FIG. 1, a transmissive glass 51 through which aprojection image P is emitted is provided on an upper surface of theprojector 1. The projection image P emitted from the transmissive glass51 is projected on the projection plane 101 such as a screen.

An operating unit 83 for a user to operate the projector 1 is alsoprovided on the upper surface of the projector 1. A focusing lever 33for a focus adjustment is provided on a side surface of the projector 1.Operating the operating unit 83 including a known input mechanism suchas buttons, a user can adjust a tint and contrast of the projectionimage P and perform setting of a network such as Internet protocoladdress (IP address) setting.

FIG. 2 is a ray diagram from the projector 1 to the projection plane101.

The projector 1 includes a light source unit (not illustrated) providedwith a light source and an image forming section 100A that forms animage using light from the light source. The image forming section 100Ais made up of an image forming unit 10 provided with a digital mirrordevice (DMD) 12 and a lighting unit 20 that reflects light from thelight source and irradiates the DMD 12 with the reflected light to causethe DMD 12 to produce an optical image. In addition, the projector 1includes a projection optical section 100B for projecting an image onthe projection plane 101. The projection optical section 100B is made upof a first optical unit 30 including at least one transmissiverefracting optical system and a coaxial first optical system 70 havingpositive power, and a second optical unit 40 including a reflectionmirror 41 and a curved mirror 42 having positive power.

The DMD 12 is irradiated with light by the lighting unit 20 thatreflects light from the light source (not illustrated), and produces animage by modulating light emitted from the lighting unit 20. The imageproduced by the DMD 12 is projected on the projection plane 101 throughthe first optical system 70 of the first optical unit 30, and thereflection mirror 41 and the curved mirror 42 of the second optical unit40.

FIG. 3 is a schematic perspective view illustrating an internalstructure of the projector 1.

As illustrated in FIG. 3, the image forming unit 10, the lighting unit20, the first optical unit 30, and the second optical unit 40 arearranged in the Y direction, which is one of the directions parallel tothe projection plane 101 and the image plane of the projection image P.A light source unit 60 is disposed on the right side of the lightingunit 20 in FIG. 3.

FIG. 3 also illustrates legs 32 a 1 and 32 a 2 of a lens holder 32(refer to FIG. 9) of the first optical unit 30, and screw fixingportions 26 g that fix the image forming unit 10 to the lighting unit 20with screws.

The structure of each unit is described in detail below.

The structure of the light source unit 60 is described below.

FIG. 4 is a schematic perspective view of the light source unit 60.

The light source unit 60 has a light source bracket 62. A light source61 such as a halogen lamp, a metal halide lamp, or a high-pressuremercury lamp is mounted above the light source bracket 62. The lightsource bracket 62 is provided with a connector 62 a that connects to apower source side connector (not illustrated) connected to a powersource unit 80 (refer to FIG. 14).

A holder 64 that holds a reflector (not illustrated), for example, isfixed with screws to a light emission side of the light source 61, whichis mounted above the light source bracket 62. An emission window 63 isprovided on a surface opposite the surface on which light source 61 isprovided of the holder 64. Light emitted from the light source 61 isconverged to the emission window 63 by the reflector (not illustrated)held by the holder 64, and emitted from the emission window 63.

Light source positioning portions 64 a 1 to 64 a 3 are provided on theupper surface of the holder 64 and on the lower surface of the holder 64at both ends in the X direction, and used for positioning the lightsource unit 60 to a lighting bracket 26 (refer to FIG. 6) of thelighting unit 20. The light source positioning portion 64 a 3 providedon the upper surface of the holder 64 is formed in a projection shapewhile the light source positioning portions 64 a 1 and 64 a 2 providedon the lower surface of the holder 64 are formed as holes.

A light source air intake port 64 b through which air flows to cool thelight source 61 is provided on a side surface of the holder 64 while alight source air exhaust port 64 c through which air heated by the lightsource 61 is discharged is provided on the upper surface of the holder64.

The light source bracket 62 is provided with a passage 65 through whichair sucked in by an air intake blower 91 (e.g., refer to FIG. 21) flows,which is described later. An opening 65 a is provided on an air flow-inside of the passage 65, i.e., on the lower left side in FIG. 4. Theopening 65 a allows part of air flowing through the passage 65 to flowbetween the light source unit 60 and an open-close cover 54 (refer toFIG. 18), which is described later. Cooling of the light source unit 60is described later.

A planar section 64 d 2 on which the light source positioning portion 64a 3 is provided and a planar section 64 d 1 on which the light sourcepositioning portions 64 a 1 and 64 a 2 are provided, both of which areillustrated in FIG. 4, are abutting sections that abut the lightingbracket 26 when being pushed by a pushing unit of the open-close cover54.

The lighting unit 20 is described below.

FIG. 5 is a perspective view illustrating optical system parts housed inthe lighting unit 20 and the other units.

As illustrated in FIG. 5, the lighting unit 20 includes a color wheel21, a light tunnel 22, two relay lenses 23, a cylinder mirror 24, and aconcave mirror 25, which are held by the lighting bracket 26. Thelighting bracket 26 has a housing-like section 261 in which the tworelay lenses 23, the cylinder mirror 24, and the concave mirror 25 arehoused. The housing-like section 261 only has a side surface on theright side in FIG. 5. The other three sides of the housing-like section261 are open. An OFF light plate 27 (refer to FIG. 6) is attached to anopening provided on the side surface on a far side in the X directionwhile a cover member (not illustrated in all of the drawings) isattached to an opening provided on the side surface on a near side inthe X direction. As a result, the two relay lenses 23, the cylindermirror 24, and the concave mirror 25 housed in the housing-like section261 of the lighting bracket 26 are covered with the lighting bracket 26,the OFF light plate 27 (refer to FIG. 6), and the cover member which isnot illustrated in all of the drawings.

The housing-like section 261 of the lighting bracket 26 has, on thelower surface thereof, an irradiation through-hole 26 d out of which theDMD 12 is exposed.

The lighting bracket 26 has three legs 29. The legs 29 abut a basemember 53 (refer to FIG. 13) and support the weights of the firstoptical unit 30 and the second optical unit 40 that are stacked andfixed on the lighting bracket 26. In addition, the legs 29 thus providedform a space through which ambient air flows to a heat sink 13 (refer toFIG. 6) serving as a cooling unit that cools the DMD 12 of the imageforming unit 10, which is described later.

FIG. 5 also illustrates legs 32 a 3 and 32 a 4 of the lens holder 32 ofthe first optical unit 30, and a screw fixing portion 45 a 3 of thesecond optical unit 40.

FIG. 6 is a perspective view when the lighting unit 20, a projectionlens unit 31, and the image forming unit 10 are viewed from direction Aof FIG. 5.

An upper surface 26 b orthogonal to the Y direction is provided on thehousing-like section 261 of the lighting bracket 26. A through-hole isprovided at each of the four corners of the upper surface 26 b (in FIG.6, only through-holes 26 c 1 and 26 c 2 are illustrated and the otherthrough-holes 26 c 3 and 26 c 4 are not illustrated). Screws for fixingthe first optical unit 30 are inserted in the through-holes. Positioningholes 26 e 1 and 26 e 2 for positioning the first optical unit 30 to thelighting unit 20 are provided adjacent to the through-holes 26 c 1 and26 c 2, respectively, located on the near side in the X direction. Inthe two positioning holes provided on the near side in the X direction,the positioning hole 26 e 1 on the color wheel 21 side is a primaryreference for the positioning and formed as a round hole while thepositioning hole 26 e 2 on a side away from the color wheel 21 is asecondary reference for the positioning and formed as an elongate holeextending in the Z direction. The surrounding area of each of thethrough-holes 26 c 1 and 26 c 2 is protruded from the upper surface 26 bof the lighting bracket 26 and serves as a positioning protrusion 26 ffor positioning the first optical unit 30 in the Y direction. Whenpositioning accuracy in the Y direction is intended to be increasedwithout the positioning protrusions 26 f, flatness of the whole uppersurface of the lighting bracket 26 needs to be increased, resulting inhigh costs. In contrast, by the positioning protrusions 26 f thusprovided, the flatness of the positioning protrusions 26 f only needs tobe increased. As a result, costs can be reduced and the positioningaccuracy in the Y direction can be increased.

A light shielding plate 262 to which the lower portion of the projectionlens unit 31 is fitted is provided to an opening on the upper surface 26b of the lighting bracket 26. The light shielding plate 262 preventslight from entering the housing-like section 261 from above.

An area between the through-holes 26 c 1 and 26 c 2 of the upper surface26 b of the lighting bracket 26 is notched so as not to hinder thefixing of the second optical unit 40 to the first optical unit 30 withscrews, which is described later.

A light source positioning receiving portion 26 a 3 having a tubularshape is provided at an end on the color wheel 21 side of the lightingbracket 26 (on the near side in the Z direction). The light sourcepositioning receiving portion 26 a 3 has a through-hole in the up-downdirection in which the light source positioning portion 64 a 3 having aprotrusion shape provided on the upper surface of the holder 64 of thelight source unit 60 (refer to FIG. 4) is fitted. Under the light sourcepositioning receiving portion 26 a 3, two light source positioningreceiving portions 26 a 1 and 26 a 2 having a protrusion shape areprovided in which the light source positioning portions 64 a 1 and 64 a2 that are formed as holes and provided on the light source bracket 62side of the holder 64 are fitted. The light source positioning portions64 a 1 to 64 a 3 of the holder 64 are fitted in the light sourcepositioning receiving portions 26 a 1 to 26 a 3 provided to the lightingbracket 26 of the lighting unit 20, resulting in the light source unit60 being positioned and fixed to the lighting unit 20 (refer to FIG. 3).

A lighting cover 28 that covers the color wheel 21 and the light tunnel22 is attached to the lighting bracket 26.

FIG. 7 is a schematic diagram to explain an optical path L of light inthe lighting unit 20.

The color wheel 21, which has a discoid shape, is fixed to a motor shaftof a color motor 21 a. The color wheel 21 has filters of red (R), green(G), and blue (B) provided in a rotational direction thereof, forexample. Light converged by the reflector (not illustrated) provided tothe holder 64 of the light source unit 60 passes through the emissionwindow 63 and reaches a circumferential edge of the color wheel 21.Light having reached the circumferential edge of the color wheel 21 isdivided into light components of R, G, and B by the rotation of thecolor wheel 21 in a time division manner.

The light components divided by the color wheel 21 enter the lighttunnel 22. The light tunnel 22 has a square tubular shape and an innercircumferential surface of the light tunnel 22 is a mirror surface.Light having entered the light tunnel 22 becomes a uniform surface lightsource while repeating reflection on the inner circumferential surfaceof the light tunnel 22 a plurality of times and is emitted toward therelay lenses 23.

Light after passing through the light tunnel 22 travels through the tworelay lenses 23, and is reflected by the cylinder mirror 24 and theconcave mirror 25, and converged on an image forming surface of the DMD12.

The image forming unit 10 is described below.

FIG. 8 is a schematic perspective view of the image forming unit 10.

As illustrated in FIG. 8, the image forming unit 10 includes a DMD board11 to which the DMD 12 is attached. The DMD 12 is attached to a socket11 a provided on the DMD board 11 such that the image forming surface,on which micro mirrors are arranged in matrix, faces upward. The DMDboard 11 is provided with a driving circuit that drives the DMD mirrors,for example. The heat sink 13 serving as the cooling unit cooling theDMD 12 is fixed to a rear surface (a surface opposite the surface onwhich the socket 11 a is provided) of the DMD board 11. A portion towhich the DMD 12 is attached of the DMD board 11 is formed as athrough-hole (not illustrated). The heat sink 13 has a protrusion 13 a(refer to FIG. 7) that is inserted in the through-hole. The tip of theprotrusion 13 a has a planer shape. The protrusion 13 a is inserted inthe through-hole (not illustrated) and the planar surface of the tip ofthe protrusion 13 a is abutted to the rear surface (the surface oppositethe image forming surface) of the DMD 12. An elastically formableheat-transfer sheet may be attached to the planar surface or the area towhich the heat sink 13 is abutted of the rear surface of the DMD 12 soas to enhance adhesiveness and thermal conductivity between the planarsurface of the protrusion 13 a and the rear surface of the DMD 12.

The heat sink 13 is pushed and fixed to the surface opposite the surfaceon which the socket 11 a is provided of the DMD board 11 by a fixingmember 14. The fixing member 14 has platy fixing sections 14 a on therear surface of the DMD board 11 on the right side and the left side inFIG. 8. Pushers 14 b are provided near one end and the other end of therespective fixing sections 14 a in the X direction so as to connect thefixing sections 14 a.

The heat sink 13 is pushed and fixed to the surface opposite the surfaceon which the socket 11 a is provided of the DMD board 11 by the fixingmembers 14 when the image forming unit 10 is fixed to the lightingbracket 26 (refer to FIG. 6) with screws.

The fixing of the image forming unit 10 to the lighting bracket 26 isdescribed below. First, the image forming unit 10 is positioned to thelighting bracket 26 such that the DMD 12 faces the opening of theirradiation through-hole 26 d provided to the lower surface of thelighting bracket 26 of the lighting unit 20, which is illustrated inFIG. 5. Then, screws are inserted in through-holes (not illustrated)provided to the fixing sections 14 a and through-holes 15 of the DMDboard 11 from below and screwed in tapped holes provided to the lowersurfaces of the screw fixing portions 26 g (refer to FIG. 3) provided tothe lighting bracket 26 so as to fix the image forming unit 10 to thelighting bracket 26. As the screws are screwed in the screw fixingportions 26 g provided to the lighting bracket 26, the pushers 14 b pushthe heat sink 13 toward the DMD board 11. As a result, the heat sink 13is pushed and fixed to the surface opposite the surface on which thesocket 11 a is provided of the DMD board 11 by the fixing member 14.

In this way, the image forming unit 10 is fixed to the lighting bracket26 and the three legs 29 illustrated in FIG. 3 also support the weightof the image forming unit 10.

A plurality of moveable micro mirrors are arranged in matrix on theimage forming surface of the DMD 12. Each micro mirror can slant amirror surface thereof at a certain angle around a torsion axis to beset to two states of “ON” and “OFF”. When set to the “ON” state, themicro mirror reflects light from the light source 61 toward the firstoptical system 70 (refer to FIG. 2) as illustrated as an arrow L2 inFIG. 7. When set to the “OFF” state, the micro mirror reflects lightfrom the light source 61 toward the OFF light plate 27 held on the sidesurface of the lighting bracket 26 illustrated in FIG. 6 (refer to anarrow L1 in FIG. 7). Accordingly, projection of light can be controlledfor each pixel of image data by driving each mirror individually,thereby enabling an image to be produced.

Light reflected toward the OFF light plate 27 (not illustrated in FIG.7) is absorbed as heat and cooled by an outside air flow.

The first optical unit 30 is described below.

FIG. 9 is a perspective view illustrating the first optical unit 30together with the lighting unit 20 and the image forming unit 10.

As illustrated in FIG. 9, the first optical unit 30 is disposed on thelighting unit 20 and includes the projection lens unit 31 holding thefirst optical system 70 made up of a plurality of lenses (refer to FIG.2) and the lens holder 32 holding the projection lens unit 31. The lensholder 32 is provided with four legs 32 a 1 to 32 a 4 extending downward(in FIG. 9, only the legs 32 a 2 and 32 a 3 are illustrated, and as forthe legs 32 a 1 and 32 a 4, refer to FIGS. 3 and 4, respectively).Tapped holes are formed on the bottom surfaces of the legs 32 a 1 to 32a 4 and used for fixing the lens holder 32 to the lighting bracket 26with screws.

The projection lens unit 31 is provided with a focusing gear 36, withwhich an idler gear 35 engages. A lever gear 34 engages with the idlergear 35. The focusing lever 33 is fixed to the rotational shaft of thelever gear 34. A tip portion of the focusing lever 33 is exposed out ofthe apparatus body (main body) as illustrated in FIG. 1.

With the movement of the focusing lever 33, the focusing gear 36 isrotated through the lever gear 34 and the idler gear 35. With therotation of the focusing gear 36, the lenses included in the firstoptical system 70 in the projection lens unit 31 are moved in respectivecertain directions, resulting in a focus of a projection image beingadjusted.

The lens holder 32 has four screw through-holes 32 c 1 to 32 c 4 throughwhich screws 48 used for fixing the second optical unit 40 to the firstoptical unit 30 are inserted (in FIG. 9, three screw through-holes 32 c1 to 32 c 3 and tip portions of the screws 48 inserted in the screwthrough-holes are illustrated). Second optical unit positioningprojections projected from the surface of the lens holder 32 are formedaround the respective screw through-holes 32 c 1 to 32 c 4 (in FIG. 9,only second optical unit positioning projections 32 d 1 to 32 d 3 areillustrated).

FIG. 10 is a sectional view along line B-B of FIG. 9.

As illustrated in FIG. 10, the legs 32 a 1 and 32 a 2 are provided withpositioning receiving projections 32 b 1 and 32 b 2, respectively. Thepositioning receiving projection 32 b 1 on the right side in FIG. 10 isinserted in the positioning hole 26 e 1 that is formed as a round holeon the upper surface 26 b of the lighting bracket 26 and serves as theprimary reference for the positioning, resulting in the lens holder 32being positioned in the Z-axis direction. The positioning receivingprojection 32 b 2 on the left side in FIG. 10 is inserted in thepositioning hole 26 e 2 that is formed as an elongate hole on the uppersurface 26 b of the lighting bracket 26 and serves as the secondaryreference for the positioning, resulting in the lens holder 32 beingpositioned in the X-axis direction. Thereafter, screws 37 are insertedin the through-holes 26 c 1 to 26 c 4 provided on the upper surface 26 bof the lighting bracket 26 and screwed in the tapped holes provided tothe legs 32 a 1 to 32 a 4 of the lens holder 32, resulting in the firstoptical unit 30 being fixed to the lighting unit 20.

An upper portion of the projection lens unit 31 with regard to the lensholder 32 is covered by a mirror holder 45 (refer to FIG. 12) of thesecond optical unit 40, which is described later. As illustrated in FIG.10, the projection lens unit 31 is exposed between the lower surface oflens holder 32 and the upper surface 26 b of the lighting bracket 26 ofthe lighting unit 20. However, no light enters an optical path of animage from the exposed portion because the projection lens unit 31 isfitted in the lens holder 32.

The second optical unit 40 is described below.

FIG. 11 is a perspective view illustrating a second optical systemincluded in the second optical unit 40, the projection lens unit 31, thelighting unit 20, and the image forming unit 10.

As illustrated in FIG. 11, the second optical unit 40 includes thereflection mirror 41 and the curved mirror 42 having a concave shapethat constitute the second optical system. A light-reflecting surface ofthe curved mirror 42 may be formed in a spherical surface, arotationally symmetric aspheric surface, or a free-form surface, forexample.

FIG. 12 is a perspective view illustrating the second optical unit 40together with the first optical unit 30, the lighting unit 20, and theimage forming unit 10.

As illustrated in FIG. 12, the second optical unit 40 also includes thetransmissive glass 51 through which an optical image reflected from thecurved mirror 42 passes and that protects the optical parts in theapparatus from dust.

The second optical unit 40 includes a mirror bracket 43 holding thereflection mirror 41 and the transmissive glass 51, a free mirrorbracket 44 holding the curved mirror 42, and the mirror holder 45 towhich the mirror bracket 43 and the free mirror bracket 44 are attached.

The mirror holder 45 has a boxy shape and areas corresponding to theupper surface, the lower surface, and a surface on the far side in the Xdirection in FIG. 12 are open. That is, the mirror holder 45 hasapproximately a c-shape from top view. Edge sections located on the nearside and the far side in the Z direction of the upper opening of themirror holder 45 extend in the X direction, and each edge section has aslanted section and a parallel section. The slanted section ascends asit extends from an edge on the near side to the far side in the Xdirection while the parallel section extends in parallel with the Xdirection. The slanted section is located on the near side in the Xdirection with regard to the parallel section. The other edge sectionlocated on the near side in the X direction of the upper opening of themirror holder 45 extends in the Z direction in parallel with the Zdirection.

The mirror bracket 43 is mounted on the mirror holder 45. The mirrorbracket 43 has a slanted surface 43 a and a parallel surface 43 b. Theslanted surface 43 a abuts the slanted sections of the edge sections ofthe upper opening of the mirror holder 45 and ascends as it extends fromthe edge on the nearside to the far side in the X direction. Theparallel surface 43 b abuts the parallel sections of the edge sectionsof the upper opening of the mirror holder 45 and is in parallel with theX direction. Each of the slanted surface 43 a and the parallel surface43 b has an opening. The reflection mirror 41 is held so as to cover theopening of the slanted surface 43 a while the transmissive glass 51 isheld so as to cover the opening of the parallel surface 43 b.

The reflection mirror 41 is positioned to and held by the slantedsurface 43 a of the mirror bracket 43 with mirror pushing members 46having a plate spring shape that push both ends of the reflection mirror41 in the Z direction to the slanted surface 43 a of the mirror bracket43. One end of the reflection mirror 41 in the Z direction is fixed bythe two mirror pushing members 46 and the other end of the reflectionmirror 41 in the Z direction is fixed by one mirror pushing member 46.

The transmissive glass 51 is positioned and fixed to the mirror bracket43 with glass pushing members 47 having a plate spring shape that pushboth ends of the transmissive glass 51 in the Z direction to theparallel surface 43 b of the mirror bracket 43. The transmissive glass51 is held by the glass pushing member 47 at each end in the Zdirection.

The free mirror bracket 44 holding the curved mirror 42 has arms 44 a onthe near side and the far side in the Z-axis direction. The arm 44 adescends as it extends from the far side to the near side in the Xdirection in FIG. 12. The free mirror bracket 44 has a connector 44 bthat connects the two arms 44 a at the upper portions of the arms 44 a.The arms 44 a of the free mirror bracket 44 are attached to the mirrorholder 45 such that the curved mirror 42 covers the opening of themirror holder 45 on the far side in the X direction.

The curved mirror 42 is pushed to the connector 44 b of the free mirrorbracket 44 by a free mirror pushing member 49 having a plate springshape at approximately a central portion of the edge thereof on thetransmissive glass 51 side. Both ends of the curved mirror 42 on thefirst optical system 70 side in the Z-axis direction are fixed to thearms 44 a of the free mirror bracket 44 with screws.

The second optical unit 40 is mounted on and fixed to the lens holder 32of the first optical unit 30. Specifically, the mirror holder 45 has atthe lower end thereof a lower surface 451 facing the upper surface ofthe lens holder 32. The lower surface 451 is provided with four screwfixing portions having a tubular shape used for fixing the mirror holder45 to the first optical unit 30 with screws (in the four screw fixingportions, as for screw fixing portions 45 a 1 and 45 a 2, refer to FIG.11, as for the screw fixing portion 45 a 3, refer to FIG. 5, and theother screw fixing portion is not illustrated). The screws 48 (refer toFIG. 9) are inserted in the respective screw through-holes 32 c 1 to 32c 3 provided to the lens holder 32 of the first optical unit 30 andscrewed to the respective screw fixing portions 45 a 1 to 45 a 3,resulting in the second optical unit 40 being fixed to the first opticalunit 30 with the screws 48. Meanwhile, the lower surface 451 of themirror holder 45 of the second optical unit 40 abuts the second opticalunit positioning projections 32 d 1 to 32 d 4, resulting in the secondoptical unit 40 being positioned and fixed in the Y direction.

As the result of the mounting and fixing of the second optical unit 40to the lens holder 32 of the first optical unit 30, the upper portion ofthe projection lens unit 31 with regard to the lens holder 32 is housedin the mirror holder 45 of the second optical unit 40 as illustrated inFIG. 9. When the second optical unit 40 is mounted on and fixed to thelens holder 32, a gap is formed between the curved mirror 42 and thelens holder 32, and the idler gear 35 (refer to FIG. 9) is disposed inthe gap.

FIG. 13 is a perspective view illustrating an optical path from thefirst optical system 70 to the projection plane 101 (screen).

A light beam after passing through the projection lens unit 31 includedin the first optical system 70 forms a conjugate intermediate image toan image produced by the DMD 12 between the reflection mirror 41 and thecurved mirror 42. The intermediate image is focused as a curved imagebetween the reflection mirror 41 and the curved mirror 42. The lightbeam dispersed after focusing of the intermediate image, enters thecurved mirror 42 having a concave shape and becomes a convergent lightbeam. The intermediate image is changed to a “further enlarged image”,projected, and focused on the projection plane 101 by the curved mirror42.

As described above, a projection optical system is made up of the firstoptical system 70 and the second optical system, and the intermediateimage is formed between the first optical system 70 and the curvedmirror 42 of the second optical system, and enlarged and projected bythe curved mirror 42. As a result, a projection distance can beshortened, thereby enabling the projector 1 to be used in a smallmeeting room, for example.

As illustrated in FIG. 13, the first optical unit 30 and the secondoptical unit 40 are mounted on and fixed to the lighting bracket 26. Theimage forming unit 10 is also fixed to the lighting bracket 26. As aresult, the legs 29 of the lighting bracket 26 receive the weights ofthe first optical unit 30, the second optical unit 40, and the imageforming unit 10 and are fixed to the base member 53.

FIG. 14 is a schematic diagram illustrating an arrangement of the unitsin the apparatus.

As illustrated in FIG. 14, the image forming unit 10, the lighting unit20, the first optical unit 30, and the second optical unit 40 arearranged in a layered manner in the Y direction, which is the short-axisdirection of the projection plane 101, while the light source unit 60 isdisposed in the Z direction, which is the long-axis direction of theprojection plane 101, relative to the layered body in which the imageforming unit 10, the lighting unit 20, the first optical unit 30, andthe second optical unit 40 are arranged in a layered manner. In theembodiment, the image forming unit 10, the lighting unit 20, the firstoptical unit 30, the second optical unit 40, and the light source unit60 are disposed in the Y direction or the Z direction that is thedirection in parallel with a projection image and the projection plane101 as described above. More specifically, the light source unit 60 isconnected to the image forming section 100A made up of the image formingunit 10 and the lighting unit 20 in a direction orthogonal to adirection in which the image forming section 100A and the projectionoptical section 100B made up of the first optical unit 30 and the secondoptical unit 40 are arranged in a layered manner. The image formingsection 100A and the light source unit 60 are arranged on a straightline parallel to the base member 53. The image forming section 100A andthe projection optical section 100B are arranged in this order from thebase member 53 on a straight line perpendicular to the base member 53.As a result, an installation space of the apparatus can be suppressedfrom being taken in a direction orthogonal to a plane of a projectionimage projected on the projection plane 101. Consequently, when theimage projection apparatus is used while placed on a desk, for example,the apparatus can be prevented from hindering the arrangement of thedesk and chairs in a small room.

In the embodiment, the power source unit 80 supplying power to the lightsource 61 and the DMD 12 is disposed above the light source unit 60 in alayered manner. The light source unit 60, the power source unit 80, theimage forming section 100A, and the projection optical section 100B arehoused in a housing of the projector 1. The housing includes the uppersurface of the projector 1, the base member 53, and an outer packagingcover 59 (refer to FIGS. 18 and 19) covering around the projector 1,which is described later.

FIG. 15 is a schematic diagram illustrating an example of use of theprojector 1 of the embodiment. FIG. 16 is a schematic diagramillustrating an example of use of a conventional projector 1A. FIG. 17is a schematic diagram illustrating an example of use of a projector 1Bin which the light source unit 60 and the lighting unit 20 are arrangedin a direction orthogonal to the projection plane 101.

As illustrated in FIGS. 15 to 17, each of the projectors 1, 1A, and 1Bis placed on a table 200 and used for projecting an image on theprojection plane 101 such as a whiteboard when used in a meeting room,for example.

As illustrated in FIG. 16, in the conventional projector 1A, the DMD 12(image forming element), the lighting unit 20, the first optical system70, and the second optical system (the curved mirror 42) are arranged inseries in a direction orthogonal to the plane of a projection imageprojected on the projection plane 101. As a result, the projector 1A islong in the direction orthogonal to the projection plane 101 (the Xdirection) and takes space in the direction orthogonal to the projectionplane 101. In general, chairs on which viewers who watch imagesprojected on the projection plane 101 sit and desks used by the viewersare arranged in the direction orthogonal to the projection plane 101.Therefore, when the projector takes space in the direction orthogonal tothe projection plane, a space for arranging the chairs and the desks islimited due to the space taken by the projector, thereby loweringconvenience.

In the projector 1B illustrated in FIG. 17, the DMD 12 (image formingelement), the lighting unit 20, and the first optical system 70 arearranged in series in a direction parallel to the plane of a projectionimage projected on the projection plane 101. Accordingly, the length ofthe projector 1B in the direction orthogonal to the projection plane 101can be shortened with regard to that of the projector 1A illustrated inFIG. 16. The projector 1B illustrated in FIG. 17, however, cannotsufficiently shorten the length thereof in the direction orthogonal tothe projection plane 101 because the light source 61 is disposed in thedirection orthogonal to the projection plane 101 relative to thelighting unit 20.

In contrast, in the projector 1 of the embodiment illustrated in FIG.15, the image forming section 100A made up of the image forming unit 10and the lighting unit 20 and the projection optical section 100B made upof the first optical unit 30 and the reflection mirror 41 are arrangedin series in the Y direction, which is one of the directions parallel tothe projection plane 101 and the image plane of a projection imageprojected on the projection plane 101. In addition, the light sourceunit 60 and the lighting unit 20 are arranged in series in the Zdirection, which is one of the directions parallel to the plane of aprojection image projected on the projection plane 101. That is, in theprojector 1 of the embodiment, the light source unit 60, the imageforming unit 10, the lighting unit 20, the first optical unit 30, andthe reflection mirror 41 are arranged in the direction parallel to theplane of a projection image projected on the projection plane 101 (the Zdirection or the Y direction), and each of the light source unit 60, theimage forming unit 10, the lighting unit 20, the first optical unit 30,and the reflection mirror 41 is disposed in parallel with the projectionplane 101 and the image plane of a projection image. Because the lightsource unit 60, the image forming unit 10, the lighting unit 20, thefirst optical unit 30, and the reflection mirror 41 are arranged in thedirection parallel to the plane of a projection image projected on theprojection plane 101 (the Z direction or the Y direction) as describedabove, the length of the projector 1 in the direction orthogonal to theprojection plane 101 (the X direction) can be shortened with regard tothose of the projectors illustrated in FIGS. 16 and 17. As a result, theprojector 1 can be prevented from causing a space for arranging chairsand desks to be reduced, thereby enabling the projector 1 to providehigher convenience.

In the embodiment, as illustrated in FIG. 14, the power source unit 80supplying power to the light source 61 and the DMD 12 is disposed abovethe light source unit 60 in a layered manner. As a result, the length inthe Z direction of the projector 1 is also reduced.

Although the second optical system includes the reflection mirror 41 andthe curved mirror 42 in the embodiment, the second optical system mayinclude only the curved mirror 42. The reflection mirror 41 may be aplanar mirror, a mirror having positive refractive power, or a mirrorhaving negative refractive power. Although the concave mirror is used asthe curved mirror 42 in the embodiment, a convex mirror can be used asthe curved mirror 42. In this case, the first optical system 70 isstructured such that no intermediate image is formed between the firstoptical system 70 and the curved mirror 42.

The light source 61 needs to be periodically replaced with a new onebecause its life span ends after being used for a certain period oftime. Therefore, the light source unit 60 is attached to the apparatusbody in a detachable manner in the embodiment.

FIG. 18 is a perspective view illustrating a placement surface side ofthe projector 1.

As illustrated in FIG. 18, the base member 53 included in the bottomsurface of the projector 1 is provided with the open-close cover 54,which is provided with a rotational operating unit 54 a. When therotational operating unit 54 a is rotated, fixing between the open-closecover 54 and the apparatus body is released and the open-close cover 54can be removed from the apparatus body. The base member 53 is providedwith a power source air intake port 56 at a position adjacent to theopen-close cover 54 in the X direction.

As illustrated in FIG. 18, an air intake port 84 and an external inputunit 88 to which image data is input from an external apparatus such asa personal computer are provided to one Y-X plane of the outer packagingcover 59 of the projector 1.

FIG. 19 is a perspective view illustrating the placement surface side ofthe projector 1 when the open-close cover 54 is removed from theapparatus.

As illustrated in FIG. 19, a surface opposite the side to which thelight source 61 is attached of the light source bracket 62 of the lightsource unit 60 is exposed when the open-close cover 54 is removed. Ahandgrip 66 is attached to the light source bracket 62 so as to berotatable to the light source bracket 62 around O₁ indicated with thedashed line in FIG. 19 as a rotational center.

To remove the light source unit 60 from the apparatus body, the lightsource unit 60 is removed through an opening of the apparatus body byrotating the handgrip 66 to grip the handgrip 66, and pulling thehandgrip 66 to the near side in FIG. 19. When the light source unit 60is attached to the apparatus body, the light source unit 60 is insertedin the opening of the apparatus body. The light source unit 60 insertedin the apparatus body is connected to a power source side connector (notillustrated) of the apparatus body with the connector 62 a illustratedin FIG. 4. The light source positioning portions 64 a 1 to 64 a 3 of theholder 64 illustrated in FIG. 4 are fitted in the light sourcepositioning receiving portions 26 a 1 to 26 a 3 provided to the lightingbracket 26 of the lighting unit 20 illustrated in FIG. 6, resulting inthe light source unit 60 being positioned to the apparatus body. As aresult, the attachment of the light source unit 60 is completed. Then,the open-close cover 54 is attached to the base member 53. Although thehandgrip 66 is provided to the light source unit 60 in the embodiment,the passage 65 that protrudes on the open-close cover 54 side asillustrated in FIG. 19 may be used as the handgrip.

The base member 53 is provided with three legs 55. A projecting amountfrom the base member 53 is changed by rotating the legs 55, therebyenabling an adjustment in a height direction (the Y direction).

As illustrated in FIG. 19, an exhaust port 85 is provided to the otherY-X plane of the outer packaging cover 59.

FIG. 20 is a schematic diagram to explain an air flow in the projector 1of the embodiment. FIG. 20 illustrates the projector 1 viewed from thedirection orthogonal to the projection plane 101 (the X direction). FIG.21 illustrates the components in the embodiment corresponding to thenumerals in FIG. 20 with the same numerals. In FIGS. 20 and 21, thearrows indicate air flow directions. FIG. 22 is a sectional view alongline C-C of FIG. 21. FIG. 23 is a sectional view along line D-D of FIG.21. FIG. 24 is a sectional view along line E-E of FIG. 21. FIG. 25 is asectional view along line F-F of FIG. 21. FIG. 26 is a sectional viewalong line G-G of FIG. 21.

As illustrated in FIG. 20, the air intake port 84 that takes ambient airinto the inside of the projector 1 is provided to one side surface (theleft side in FIG. 20) of the projector 1 while the exhaust port 85 thatdischarges air inside the projector 1 is provided to the other sidesurface (the right side in FIG. 20) of the projector 1. An exhaust fan86 is provided so as to face the exhaust port 85.

Parts of the exhaust port 85 and the air intake port 84 are provided soas to be between the light source unit 60 and the operating unit 83 whenthe projector 1 is viewed from the direction orthogonal to theprojection plane 101 (the X direction). As a result, ambient air takenin from the air intake port 84 flows in the Z-Y plane of the mirrorholder 45 and the rear surface of the curved mirror 42 in the secondoptical unit 40 illustrated in FIG. 12 and toward the air intake port 84along the mirror holder 45 and a curved surface of the rear surface ofthe curved mirror 42 (refer to FIGS. 22, 24, and 26). The power sourceunit 80 disposed above the light source unit 60 has an arch-like shapewhen viewed from the Z direction. Air flowing from the air intake port84 along the mirror holder 45 and the curved surface of the rear surfaceof the curved mirror 42 flows in a space surrounded by the power sourceunit 80, and is discharged from the exhaust port 85. The curved mirror42 has a concave shape and the positive power as described above. Therear surface of the curved mirror 42 has a convex shape approximatelyconforming to the shape of the front surface of the curved mirror 42.The exhaust port 85, the air intake port 84, and the curved mirror 42are arranged on a straight line.

The arrangement of the exhaust port 85 and part of the air intake port84 provided so as to be between the light source unit 60 and theoperating unit 83 when the projector 1 is viewed from the directionorthogonal to the projection plane 101 (the X direction) enables an airflow to be produced that passes through the space between the lightsource unit 60 and the operating unit 83 and is discharged from theexhaust port 85. In addition, a space in which air can flow is providedbetween the curved mirror 42 and the outer packaging cover 59 (refer toFIGS. 22, 24, and 26) and ambient air taken in from the air intake port84 flows along the rear surface of the curved mirror 42, i.e., thecurved surface of the surface that is not used as a reflection surface,and reaches the exhaust port 85. This structure has a cooling effect onthe curved mirror 42 and also achieves a flow path having a very lowloss in flow rate.

In FIG. 22, the three arrows illustrate an air flow between the outerpacking cover 59 and the rear surface of the curved mirror 42. This airflow is also above the light source unit 60 (obscured in FIG. 22, butwhose location is clear in FIG. 20 and FIG. 21) and below the operatingunit 83.

A light source blower 95 is disposed at such a position that the lightsource blower 95 can take in air surrounding the color motor 21 a (referto FIG. 5) rotating the color wheel 21 of the lighting unit 20 (refer toFIG. 25). As a result, an air flow produced by air sucked in by thelight source blower 95 can cool the color motor 21 a.

Air taken in by the light source blower 95 flows through a light sourceduct 96 and flows in the light source air intake port 64 b of the holder64 (refer to FIG. 4). Part of air having flowed in the light source duct96 flows through an opening 96 a formed on a surface facing the outerpackaging cover 59 (refer to FIG. 19) of the light source duct 96through the space between a light source housing 97 and the outerpackaging cover 59.

Air flowing in the space between the light source housing 97 and theouter packaging cover 59 through the opening 96 a of the light sourceduct 96 cools the light source housing 97 and the outer packaging cover59, and thereafter is discharged from the exhaust port 85 by the exhaustfan 86.

Air flowing in the light source air intake port 64 b flows in the lightsource 61, cools the light source 61, and thereafter is discharged fromthe light source air exhaust port 64 c provided on the upper surface ofthe holder 64. Air discharged from the light source air exhaust port 64c flows through an opening on the upper surface of the light sourcehousing 97 toward the exhaust port 85 along a fluid guide 87.Thereafter, the air mixes with low temperature air flowing in the spacesurrounded by the power source unit 80 after flowing through the secondoptical unit 40, and is then discharged from the exhaust port 85 by theexhaust fan 86. In this way, high temperature air discharged from thelight source air exhaust port 64 c mixes with ambient air before beingdischarged, thereby enabling air discharged from the exhaust port 85 tobe prevented from reaching high temperature. The fluid guide 87 is notalways required. Without the fluid guide 87, high temperature airdischarged from the light source air exhaust port 64 c is dischargedfrom the exhaust port 85 by air flowing toward the exhaust port 85 fromthe air intake port 84 through the rear surface of the curved mirror 42,in a space surrounded by a main PFC power source board 80 a and a subPFC power source board 80 b, which are described later. However, the useof the fluid guide 87 can prevent high temperature air discharged fromthe light source air exhaust port 64 c from flowing directly to the mainPFC power source board 80 a and flowing in the vicinity of the sub PFCpower source board 80 b. However, when the fluid guide 87 is used forflowing all high temperature air off the main PFC power source board 80a and the sub PFC power source board 80 b, all high temperature air doesnot mix with air flowing on the rear surface of the curved mirror 42,i.e., the temperature is not lowered, and is discharged from the exhaustport 85, resulting in the temperature of the exhaust port 85 beingincreased. Accordingly, in a case in which some of the air that isdischarged from the light source air exhaust port 64 c and flows throughthe fluid guide 87 flows through the space surrounded by the main PFCpower source board 80 a and the sub PFC power source board 80 b, the aircan reliably mix with air flowing on the rear surface of the curvedmirror 42 from the air intake port 84 and toward the exhaust port 85,which is safe for a user.

The operating unit 83 for a user to operate the apparatus is preferablyprovided on the upper surface of the apparatus for allowing the user toreadily operate the apparatus. In the embodiment, the transmissive glass51 used for projecting an image on the projection plane 101 is providedon the upper surface of the projector 1. Because of the structure, theoperating unit 83 needs to be provided such that part of the operatingunit 83 overlaps with the light source unit 60 when the projector 1 isviewed from the Y direction, i.e., from top view of the projector 1.That is, when the operating unit 83 is assumed as an operation planehaving a certain area, the light source unit 60 is disposed on thenormal line of any area of the operation plane. It can be also said thatthe light source unit 60 and the operating unit 83 are disposed on thenormal line extended from the base member 53 having a platy shape.

In the embodiment, air having high temperature after cooling the lightsource 61 is discharged toward the exhaust port 85 by an air flowflowing from the air intake port 84 toward the exhaust port 85 in thespace between the light source unit 60 and the operating unit 83,thereby enabling high temperature air to be prevented from flowing tothe operating unit 83. As a result, an increase in the temperature ofthe operating unit 83 due to air having high temperature after coolingthe light source 61 can be suppressed. In addition, part of air flowingfrom the air intake port 84 toward the exhaust port 85 through thesecond optical unit 40 flows directly under the operating unit 83 andcools the operating unit 83. This air flow can also suppress an increasein the temperature of the operating unit 83.

Air suction by the exhaust fan 86 causes ambient air to be sucked infrom the power source air intake port 56 provided to the base member 53illustrated in FIG. 18. A ballast substrate 3 a (refer to FIGS. 24 and25) that supplies stable power (current) to the light source 61 isdisposed on the far side in the X-direction in FIG. 21 with regard tothe light source housing 97. Ambient air taken in from the power sourceair intake port 56 cools the ballast substrate 3 a while flowing upwardin the space between the light source housing 97 and the ballastsubstrate 3 a. Thereafter, the air flows in the space surrounded by thepower source unit 80 disposed above the ballast substrate 3 a and isthen discharged from the exhaust port 85 by the exhaust fan 86.

In the embodiment, a fan that generates an air flow flowing from the airintake port 84 toward the exhaust port 85 is provided on the exhaustside as the exhaust fan 86, thereby enabling a supplying amount of airsupplied to the inside of the apparatus from the air intake port 84 tobe further increased than a case when the fan is provided to the airintake port 84. When the fan is provided to the air intake port 84, thevolume of ambient air supplied from the fan to the inside of theapparatus is reduced by the second optical unit 40 because the secondoptical unit 40 is disposed in a direction in which the fan sends air.In contrast, when the fan is disposed on the exhaust port 85 side as theexhaust fan 86, the volume of air discharged by the exhaust fan 86 isnot reduced because no obstacles are usually disposed on an air exhaustside of the exhaust port 85. Accordingly, air of the same amount as airdischarged by the exhaust fan 86 is taken in from the air intake port84, resulting in a supplying amount of air supplied from the air intakeport 84 to the inside of the apparatus not being reduced. As a result,air can flow at a certain pressure from the air intake port 84 towardthe exhaust port 85, thereby enabling heated air ascending from thelight source 61 to be well directed toward the exhaust port 85 by theair flow flowing from the air intake port 84 to the exhaust port 85.

On the lower left side of the apparatus body in FIG. 20, a coolingsection 120 is disposed that cools the heat sink 13 of the image formingunit 10 and the light source bracket 62 of the light source unit 60, forexample. The cooling section 120 includes the air intake blower 91, avertical duct 92, and a horizontal duct 93.

The air intake blower 91 is disposed under the air intake port 84 so asto face the air intake port 84. The air intake blower 91 sucks inambient air through the air intake port 84 from a surface thereof facingthe air intake port 84 and sucks in air inside the apparatus fromanother surface opposite the surface facing the air intake port 84, andsupplies the sucked air to the vertical duct 92 disposed below the airintake blower 91. Air flowing in the vertical duct 92 flows downward andto the horizontal duct 93 connected to the downward portion of thevertical duct 92.

In the horizontal duct 93, the heat sink 13 is disposed. The heat sink13 is cooled by air flowing in the horizontal duct 93. The heat sink 13cooled in this way can efficiently cool the DMD 12 and prevent the DMD12 from reaching high temperature.

Air after flowing in the horizontal duct 93 flows through the passage 65or the opening 65 a provided to the light source bracket 62 of the lightsource unit 60 illustrated in FIG. 4. Air after flowing in the opening65 a flows in the space between the open-close cover 54 and the lightsource bracket 62, and cools the open-close cover 54.

On the other hand, air flowing through the passage 65 cools the lightsource bracket 62 and thereafter flows in a space opposite the emissionside of the light source 61 to cool a side opposite the reflectionsurface of the reflector of the light source 61, thereby cooling thereflector of the light source 61. That is, air flowing through thepassage 65 takes away heat from both the light source bracket 62 and thelight source 61. Air passed through the vicinity of the reflector flowsthrough an exhaust duct 94 that guides air existing from the level ofthe light source bracket 62 to approximately the lower portion of theexhaust fan 86, and thereafter mixes with air discharged from the lightsource air exhaust port 64 c and reaches the exhaust port 85 through thefluid guide 87. Then, the air is discharged via the exhaust port 85 bythe exhaust fan 86. Air flowing in the space between the open-closecover 54 and the light source bracket 62 through the opening 65 a coolsthe open-close cover 54 and thereafter flows in the inside of theapparatus and is discharged from the exhaust port 85 by the exhaust fan86.

In the projector 1 of the embodiment, the image forming section 100A(the image forming unit 10 and the lighting unit 20) and the projectionoptical section 100B (the first optical unit 30 and the second opticalunit 40) are disposed in the Y direction (up-down direction) in alayered manner, and an image is projected from the upper surface of theprojector 1 toward the projection plane 101. In addition, the lightsource unit 60 is disposed in the Z direction relative to the lightingunit 20, thereby shortening the length of the projector 1 in thedirection orthogonal to the projection plane 101 (the X direction). Theoperating unit 83 for a user to operate the apparatus is preferablyprovided on the upper surface of the projector 1 for allowing the userto readily operate the apparatus. In the embodiment, the transmissiveglass 51 used for projecting an image on the projection plane 101 isprovided on the upper surface of the projector 1. Because of thestructure, the operating unit 83 needs to be provided in such a positionthat the operating unit 83 overlaps with the light source 61 when theprojector 1 is viewed from the Y direction.

When the operating unit 83 is disposed in such a position that theoperating unit 83 overlaps with the light source 61 when the projector 1is viewed from the Y direction as described above, air heated by thelight source 61 ascends to and collides with the operating unit 83, andthe operating unit 83 may reach high temperature.

In the embodiment, ascending air heated by the light source 61 isdischarged toward the exhaust port 85 by an air flow flowing from theair intake port 84 toward the exhaust port 85 in the space between thelight source unit 60 and the operating unit 83 as describe above,thereby enabling the heated air to be prevented from colliding with theoperating unit 83 and the operating unit 83 from reaching hightemperature. Even if the ascending air collides with the operating unit83, air heated by the light source 61 mixes with low temperature airtaken in from the air intake port 84, resulting in the temperature beinglowered, and collides with the operating unit 83. As a result, anincrease in the temperature of the operating unit 83 can be suppressed.In addition, part of air flowing from the air intake port 84 toward theexhaust port 85 cools the operating unit 83 while flowing directly underthe operating unit 83. This air flow can also suppress an increase inthe temperature of the operating unit 83.

Air heated through the light source housing 97 by thermal conduction andradiation heat from the light source 61 also ascends toward theoperating unit 83 disposed above the light source 61. The heated air canalso flow toward the exhaust port 85 by the air flow flowing from theair intake port 84 to the exhaust port 85. As a result, the collision ofthe heated air with the operating unit 83 is suppressed, therebyenabling an increase in the temperature of the operating unit 83 to besuppressed.

As illustrated in FIG. 27, a mixing duct 98 that receives air dischargedfrom the light source and ascending from the light source housing 97 andmixes the discharged air with low temperature air flowing from the airintake port 84 may be provided between the light source 61 and theoperating unit 83.

As illustrated in FIG. 27, the ends of the mixing duct 98 on the nearside and the far side in the Z-axis direction are open. The light sourcehousing 97 is provided with a light source exhaust duct 99 that forms aflow path guiding air discharged from the light source upward in thevertical direction and causes the discharged air to flow in the mixingduct 98. One end of the light source exhaust duct 99 is connected to anopening of the light source housing 97 formed just above the lightsource air exhaust port 64 c of the holder 64 while the other end of thelight source exhaust duct 99 is connected to an opening provided to alower surface of the mixing duct 98.

Air temperature which is increased by taking heat of the light source 61discharged from the light source air exhaust port 64 c of the holder 64ascends in the light source exhaust duct 99 by its ascending aircurrent, suction power of the exhaust fan 86, and wind pressure of thelight source blower 95, for example, and collides with an upper surfaceserving as a wall surface of the mixing duct 98.

Air after the collision with the upper surface of the mixing duct 98mixes with low temperature air flowing in the mixing duct 98 through aninflow vent 98 a opened on the left side of the mixing duct 98 in FIG.27 from the air intake port 84 and through the second optical unit 40.As a result, the temperature of air discharged from the light source islowered and the air flows toward the exhaust fan 86. The air of whichthe temperature is lowered flows out from an outflow vent 98 b opened onthe exhaust fan 86 side of the mixing duct 98. The outflow mixes withair flowing from an outer circumference of the mixing duct 98 and thetemperature of mixed air is further lowered, and thereafter the mixedair is discharged outside the apparatus by the exhaust fan 86.

The mixing duct 98 thus provided can prevent air heated by the lightsource 61 from colliding with the operating unit 83.

The descriptions above are represented by way of example, and theinvention provides particular effects in the following aspects (1) to(3).

(1) In the image projection apparatus including the light source unit60, the image forming section 100A that forms an image using light fromthe light source unit 60 (in the embodiment, the image forming section100A is made up of the image forming unit 10 and the lighting unit 20),the curved mirror 42 having a concave shape, the projection opticalsection 100B that projects the image (in the embodiment, made up of thefirst optical unit 30 and the second optical unit 40), and the operatingunit 83 for a user to operate the apparatus, the operating unit 83 isdisposed on the upper surface of the apparatus and above the lightsource unit 60. The apparatus further includes the air intake port 84that takes ambient air into the inside of the apparatus, the exhaustport 85 that discharges air inside the apparatus, and the air supplyingunit such as the exhaust fan 86 that supplies air by sucking in ambientair from the air intake port 84 and supplying air so as to exhaust airfrom the exhaust port 85. At least part of the air intake port 84 and atleast part of the exhaust port 85 are disposed so as to be between thelight source unit 60 and the operating unit 83. The curved mirror 42having a concave shape is disposed such that air flowing from the airintake port 84 toward the exhaust port 85 flows along the rear surfaceof the curved mirror 42.

This structure produces an air flow flowing from the air intake porttoward the exhaust port in the space between the light source unit 60and the operating unit 83 as described in the embodiment. This air flowenables ascending air heated by heat of the light source unit 60 to flowtoward the exhaust port 85 and to be discharged. As a result, thecollision of air heated by the light source unit 60 with the operatingunit 83 disposed above the light source unit 60 can be suppressed and anincrease in the temperature of the operating unit 83 can be suppressed.In addition, the curved mirror 42 having a concave shape is disposedsuch that air flowing from the air intake port 84 toward the exhaustport 85 flows along the rear surface of the curved mirror 42 having aconcave shape, enabling ambient air taken in from the air intake port 84to flow in the space between the light source 61 in the apparatus andthe operating unit 83 while maintaining its momentum when taken in anddischarged from the exhaust port 85. Air heated by the light source 61mixes with low temperature air and is discharged from the exhaust port85 as describe above, thereby enabling air discharged from the exhaustport 85 to be prevented from reaching high temperature.

(2) In the image projection apparatus according to the first aspect, theair supplying unit is provided to the exhaust port 85 side.

This structure enables a supplying amount of air capable of being takeninto the inside of the apparatus to be further increased than a casewhen the air supplying unit is provided to the air intake port 84 sideas described in the embodiment. As a result, air heated by the lightsource 61 can be well transferred to the exhaust port 85 by the air flowflowing from the air intake port 84 toward the exhaust port 85.

(3) In the image projection apparatus according to any one of the firstand the second aspects, the projection optical section 100B is disposedon the image forming section 100A while the light source 61 and theimage forming section 100A are arranged in a direction in parallel witha plane of a projection image projected on the projection plane 101 andthe apparatus body, and the image is projected from the upper surface ofthe apparatus toward the projection plane 101.

This structure enables the length of the apparatus in a directionorthogonal to the projection plane 101 to be shortened. As a result, aninstallation space of the apparatus can be prevented from being largelytaken in the direction orthogonal to the plane of a projection imageprojected on the projection plane 101. Consequently, when the imageprojection apparatus is used while placed on a desk, for example, theapparatus can be prevented from hindering the arrangement of the deskand chairs in a small room.

According to the embodiments, air that is heated by the light source andascends in the apparatus and heated air are caused to flow toward theexhaust port through a second flow path formed between the light sourceand the operating unit, thereby enabling the operating unit to befurther suppressed from being heated than in conventional ways. Air thatis heated by heat conducted from the light source by thermal conductionand the light source and ascends in the apparatus mixes with air flowingin the second flow path different from a first flow path, therebylowering the temperature of the air. Consequently, an increase in thetemperature of the operating unit can be suppressed even when theoperating unit is disposed above the light source when viewed from theplacement surface on which the apparatus body is placed.

Although the invention has been described with respect to specificembodiments for a complete and clear disclosure, the appended claims arenot to be thus limited but are to be construed as embodying allmodifications and alternative constructions that may occur to oneskilled in the art that fairly fall within the basic teaching herein setforth.

What is claimed is:
 1. An image projector, comprising: a user interfaceto input information from a user; a light source to emit light; an imagegenerator to generate an image using the light source; a concave mirrorto reflect the image from the image generator; and a cover to cover atleast the concave mirror, wherein air flowing between the light sourceand the user interface passes between a rear surface of the concavemirror and the cover.
 2. The image projector according to claim 1,further comprising: an air intake port on the cover; and an air exhaustport on the cover, wherein the air intake port, the air exhaust port,and the concave mirror are arranged on a straight line.
 3. An imageprojector, comprising: a user interface to input information from auser; a light source to emit light; an image generator to generate animage using the light source; a concave mirror to reflect the image fromthe image generator, wherein air flowing between the light source andthe user interface passes through a path defined by at least a rearsurface of the concave mirror.
 4. The image projector according to claim3, further comprising: a cover; and an air exhaust port on the cover,wherein the air exhaust port and the concave mirror are arranged in astraight line.